Depth capture refers to systems and techniques that use light projectors and cameras to obtain three-dimensional information about a scene. A depth capture, three-dimensional image of a person's face, for example, includes X, Y and Z coordinates of points that lie on surface features such as the eyes, nose and mouth.
Depth capture systems facilitate richer human-machine interactions such as gesture inputs for computer software. Machine inputs that are made with computer mice or TV remote controls today may be replaced by gestures such as waving or throwing motions in the future. Depth capture is valuable in manufacturing where robots need precise three-dimensional coordinates of products they are assembling. Depth capture may also be used to take body measurements for custom fit clothing or to locate body parts during robotic surgical procedures.
Two common depth capture techniques are structured light and time-of-flight. In structured light a known light pattern is projected onto an object. The surface contours of the object make the pattern appear distorted when viewed with a camera at a vantage point separated from the pattern projector by a baseline distance. Using geometrical relationships, the distortions are used to determine the distance from the projector to points on the object. Time-of-flight is based on measuring the time required for light to travel from a light source to an object and back to a camera. The farther away the object is, the longer the light takes to make the round trip.
Structured light systems generally offer more precise depth measurements than time-of-flight systems and are more commonly used when the object of interest is nearby. Time-of-flight systems are usually not as precise, but work over greater distances than structured light. There are many other tradeoffs that make one type of depth capture system more suitable than another for a particular task.
What are needed are depth capture systems and techniques that include the best characteristics of structured light and time-of-flight.